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http://dx.doi.org/10.2147/OPTH.S127579

interactive navigation-guided ophthalmic plastic surgery: the utility of 3D CT-DCg-guided dacryolocalization in secondary acquired lacrimal duct obstructions

Mohammad Javed ali1

swati singh1

Milind n naik1

swathi Kaliki2

Tarjani Vivek Dave1

1govindram seksaria institute of Dacryology, 2The Operation eyesight Universal institute for eye Cancer, l V Prasad eye institute, hyderabad, Telangana, india

Aim: The aim of this study was to report the preliminary experience with the techniques and

utility of navigation-guided, 3D, computed tomography–dacryocystography (CT-DCG) in the

management of secondary acquired lacrimal drainage obstructions.

Methods: Stereotactic surgeries using CT-DCG as the intraoperative image-guiding tool were

performed in 3 patients. One patient had nasolacrimal duct obstruction (NLDO) following a

complete maxillectomy for a sinus malignancy, and the other 2 had NLDO following extensive

maxillofacial trauma. All patients underwent a 3D CT-DCG. Image-guided dacryolocaliza-

tion (IGDL) was performed using the intraoperative image-guided StealthStation™ system

in the electromagnetic mode. All patients underwent navigation-guided powered endoscopic

dacryocystorhinostomy (DCR). The utility of intraoperative dacryocystographic guidance and

the ability to localize the lacrimal drainage system in the altered endoscopic anatomical milieu

were noted.

Results: Intraoperative geometric localization of the lacrimal sac and the nasolacrimal duct

could be easily achieved. Constant orientation of the lacrimal drainage system was possible while

navigating in the vicinity of altered endoscopic perilacrimal anatomy. Useful clues with regard

to modifications while performing a powered endoscopic DCR could be obtained. Surgeries

could be performed with utmost safety and precision, thereby avoiding complications. Detailed

preoperative 3D CT-DCG reconstructions with constant intraoperative dacryolocalization were

found to be essential for successful outcomes.

Conclusion: The 3D CT-DCG-guided navigation procedure is very useful while performing

endoscopic DCRs in cases of secondary acquired and complex NLDOs.

Keywords: CT-dacryocystography, image guidance, navigation, lacrimal drainage, nasolacrimal

duct obstruction, powered endoscopic DCR

IntroductionIn recent times, we are seeing an increased interest in the use of interactive image-

guided surgeries for complex lacrimal drainage disorders.1–3 The advantages of

stereotactic guidance, also referred to as image or navigation guidance, include

increased anatomical orientation, accurate target localization and trajectory infor-

mation, minimal collateral damage, enhanced safety and surgeon comfort during

lacrimal procedures, specifically the endoscopic approaches. Computed tomography

(CT)–dacryocystography (DCG) is a well-established modality of lacrimal imaging

and is useful in delineating the lacrimal drainage system from the surrounding tissues

Correspondence: Mohammad Javed aligovindram seksaria institute of Dacryology, l V Prasad eye institute, road no 2, Banjara hills, hyderabad 500034, Telangana, indiaemail drjaved007@gmail.com

Journal name: Clinical OphthalmologyArticle Designation: Original ResearchYear: 2017Volume: 11Running head verso: Ali et alRunning head recto: 3D CT-DCG-guided stereotactic surgeriesDOI: http://dx.doi.org/10.2147/OPTH.S127579

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ali et al

and assessing the stenosis, dilatation or mass lesion within

the lacrimal ducts.4–7 Although it is not routinely required in

primary dacryocystorhinostomy (DCR) and routine second-

ary acquired nasolacrimal duct obstruction (SALDO) cases,

it may be of value in cases of complex SALDO. The 3D

reconstruction of the CT-DCG has been reported to allow

the surgeon to view images in multiple projections and to

enhance the accuracy of diagnosing pathologies.4 The authors

of this study report their preliminary experiences with naviga-

tion guidance for lacrimal drainage surgeries using the 3D

CT-DCG as the basic guiding tool.

MethodologyApproval from the institutional review board of L V Prasad

Eye Institute was obtained. Patient consents for both the

surgery and the publication of their reports and photos were

obtained. Three consecutive patients with complex second-

ary acquired NLDO were included in this study. Complex

SALDO was defined as a case of SALDO in which the lac-

rimal and the perilacrimal soft tissue or bony anatomy was

grossly altered as per CT, or when routine bony landmarks

were unavailable for intraoperative guidance for localization

of the sac. Stereotactic surgeries were performed in these

3 patients using 3D CT-DCG, thereby enabling the high-

lighted lacrimal sac as the radiologic landmark and as the

intraoperative image-guiding tool. All patients underwent

a 3D CT-DCG. Image-guided dacryolocalization (IGDL)

was performed using the intra-operative image-guided

StealthStation™ system in the electromagnetic mode

using the AxiEM™ technology. All patients underwent

navigation-guided powered endoscopic DCR. The utility of

intraoperative DCG guidance and the ability to localize the

lacrimal drainage system in the altered endoscopic anatomi-

cal milieu were noted.

For intraoperative navigation, contiguous CT scans of

1 mm thickness were performed from the superior aspect of

the horizontal portion of the mandible to the vertex as per

the manufacturer’s guidelines for image-guided acquisition.

DCG was performed using the nonionic, water-soluble con-

trast medium (Iohexol, 755 mg/mL). The contrast was diluted

50:50 with normal saline and injected slowly into the lacri-

mal drainage system with the help of lacrimal canula. Once

CT-DCG images were acquired, the slices were reconstructed

to sub-1 mm thickness, and 3D reconstruction was performed

on the CT workstation after adjusting the Hounsfield values

to detect the contrast density (Figure 1). Various scans were

then uploaded to the navigation system and merged using

the StealthStation Merger software to create a 3D model

of the lacrimal drainage system for real-time tracking. The

patient location was then registered and the navigation system

could accurately demonstrate the location of an anatomical

point radiologically in all the 3 CT-DCG planes.

ResultsWe illustrate 3 cases here to demonstrate the utility of DCG

image guidance in complex lacrimal surgeries.

Case 1A female, aged 67 years, was referred for management of

right-sided nasolacrimal duct obstruction (NLDO) follow-

ing a total right-sided maxillectomy. She was a known case

with maxillary sinus carcinoma and had undergone a right

Figure 1 Case 1: (A) endoscopic photograph of the right nasal cavity showing the palatal defect, exposed bone of the lateral wall in the area of maxillary sinus and altered anatomy of the lateral wall. (B) The 3D CT-DCg showed absence of the right maxilla with right dilated lacrimal sac and an abrupt obstruction at the sac–duct junction. The DCG findings of the left lacrimal apparatus were normal.Abbreviations: CT, computed tomography; DCg, dacryocystography.

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3D CT-DCg-guided stereotactic surgeries

maxillectomy along with hemipalatal excision (Figure 1A)

and was stable since then without any recurrence. She

used a palatal prosthesis to prevent nasal regurgitation of

oral contents during eating. The left lacrimal apparatus

was normal. Endoscopic examination of the right nasal

cavity showed gross alteration of the nasal anatomy

(Figure 1A). There was no palpable bony lateral wall of the

nose below the sac–duct junction. The area of the maxil-

lary sinus was replaced by an exposed bone (Figure 1A)

without a mucosal covering and a large hemipalatal defect

(Figure 1A). The 3D CT-DCG showed absence of the

right maxilla with right dilated lacrimal sac and an abrupt

obstruction at the sac–duct junction (Figure 1B). The

DCG findings of the left lacrimal apparatus were normal

(Figure 1B). Navigation guidance using the CT-DCG was

used to accurately delineate the boundaries of the dilated

lacrimal sac (IGDL) (Figure 2) before proceeding with a

continuous navigation-guided powered endoscopic DCR.

Intraoperatively, the 3D-reconstructed CT-DCG virtual

models were utilized (Figure 3) to constantly orient the

surgeon to navigate in an altered anatomical milieu. There

were no complications. The stereotactic image guidance in

this case facilitated accurate localization of the obstructed

lacrimal drainage apparatus, and this information helped

the surgeon in precise planning and safe execution of the

endoscopic surgery.

Case 2A male, aged 42 years, presented with complaints of left-sided

epiphora and discharge over 1-year duration. The complaints

started after the patient sustained facial injuries with orbital

fractures following a road traffic accident. Lacrimal evaluation

showed a left-sided mucocele with regurgitation of mucoid

material. The right lacrimal system was normal. Endoscopic

examination of the left nasal cavity showed alteration of the

nasal anatomy with axillary fracture of the middle turbinate

and completely exposed maxillary sinus (Figures 4 and 5).

The 3D CT-DCG showed an irregular dilated left lacrimal

sac and an abrupt obstruction at the level of the proximal

nasolacrimal duct (Figure 4B). The DCG findings of the right

lacrimal apparatus were normal (Figure 4B). IGDL revealed

useful clues on the altered location of the lacrimal sac in rela-

tion to the endoscopic lateral wall anatomy (Figure 5A). IGDL

in combination with 3D CT-DCG provided precise geometric

orientation during the continuous navigation-guided powered

endoscopic DCR (Figure 5B).

Figure 2 Case 1: image-guided dacryolocalization view showing the coronal (upper left), sagittal (upper right) and axial (lower left) CT images, as well as the endoscopic view (lower right).Note: Note that the intersection of crosshairs shows the simultaneous endoscopic localization of the contrast-filled lacrimal sac.Abbreviation: CT, computed tomography.

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Figure 3 Case 1: intraoperative image-guided view depicting the image-guided dacryolocalization using the 3D-reconstructed virtual model of the DCg (lower right panel).Note: note the sac being delineated as the red lesion being actively tracked by the blue endoscopic probe.Abbreviation: DCg, dacryocystography.

Figure 4 Case 2: (A) endoscopic view of the left nasal cavity showing alteration of the nasal anatomy. (B) The 3D CT-DCg shows an irregular dilated left lacrimal sac and an abrupt obstruction at the level of the proximal nasolacrimal duct. The DCG findings of the right lacrimal apparatus were normal.Abbreviations: CT, computed tomography; DCg, dacryocystography.

Case 3A male, aged 43 years, was referred for management of

right-sided posttraumatic NLDO. The patient had right-

sided epiphora and discharge over a duration of 2 years. The

complaints started after the patient had a road traffic acci-

dent with resultant orbital fractures of the medial wall and

floor. Lacrimal evaluation was suggestive of right complete

NLDO. The left lacrimal system was suggestive of a partial

obstruction of the NLDO. The 3D CT DCG showed a regu-

larly dilated right lacrimal sac and an abrupt obstruction at

the level of the sac–duct junction (Figure 6A). The DCG find-

ings of the left lacrimal apparatus showed multiple areas of

stenosis at the sac–duct junction and within the nasolacrimal

duct (Figure 6A). IGDL could obtain the precise location

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Figure 5 Case 2: (A) image-guided dacryolocalization view showing the CT images and the endoscopic view (lower right). note that the intersection of crosshairs shows the simultaneous endoscopic localization of the contrast-filled lacrimal sac. (B) active endoscopic real-time tracking of the lacrimal apparatus using the 3D virtual model.Abbreviation: CT, computed tomography.

Figure 6 Case 3: (A) The 3D CT-DCG showed a regularly dilated right lacrimal sac and an abrupt obstruction at the level of the sac–duct junction. The DCG findings of the left lacrimal apparatus showed multiple areas of stenosis at the sac–duct junction and within the nasolacrimal duct. (B) Endoscopic localization of the contrast-filled sac. note that the green crosshairs depict the accurate localization on all the CT images.Abbreviations: CT, computed tomography; DCg, dacryocystography.

of the lacrimal sac in relation to the endoscopic lateral wall

anatomy (Figure 6B). Following exposure of the presumed

lacrimal tissues during the endoscopic DCR, intraoperative

IGDL was able to successfully delineate the lacrimal

apparatus from the surrounding areas of intense scarring

(Figure 7). The surgery was completed safely without

any complications.

DiscussionThis study presents our preliminary report on image-guided

lacrimal surgeries using 3D CT-DCG for stereotactic navi-

gation. All the illustrated cases would have been difficult to

operate by the conventional method with a mere CT scan as

a guideline and, therefore, reflect the utility of DCG guidance

in the management of complex secondary acquired lacrimal

duct obstructions.

CT-DCG is one among the established modalities of

imaging the lacrimal drainage apparatus and is known to

help delineate the site of obstructions, differentiate between

varying degrees of stenosis and aid in the detailed study

of lacrimal mass lesions. Freitag et al4 showed that the 3D

reconstruction of CT-DCG was superior to that using plain

2D CT-DCG because the entire column of the dye could

be assessed in multiple planes. In addition, 3D-DCG was

found to be useful in detecting subclinical partial obstruc-

tions, assessing the causes of a DCR failure and delineating

the precise anatomy for better surgical planning in complex

cases. The current series utilized these distinct advantages,

in addition to the stereotactic or navigation-guided powered

endoscopic DCR’s benefits.

Navigation guidance for complex lacrimal surgeries using

plain CT scan has been reported thrice earlier. Day et al1

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Figure 7 Case 3: intraoperative active localization of the lacrimal apparatus following the osteotomy.Note: note the accurate localization in the sagittal plane depicting the geometric level of the probe and correlate that to the endoscopic tissue localization.

reported a 53-year-old man with bilateral NLDO secondary to

cocaine abuse. The oronasal fistula, obliteration of meati and

extensive endoscopic anatomical alteration necessitated the

use of navigation guidance for the endoscopic DCR. Morley

et al2 reported a 54-year-old man with left iatrogenic NLDO

secondary to left rhinectomy and hemimaxillectomy for a

sinonasal carcinoma. Navigation-guided placement of Lester

Jones tube into the contralateral nasal cavity was successfully

executed with the help of intraoperative navigation guidance.

Ali et al3 coined the term “image-guided dacryolocaliza-

tion” or IGDL to encompass the use of stereotactic naviga-

tion in lacrimal disorders. They reported 3 patients with

gross nasoorbitoethmoid fractures with secondary acquired

NLDOs. They showed that navigation guidance facilitates

safe and precise surgeries in complex lacrimal disorders.

The limitations of these procedures could be the possible

risk of iatrogenic trauma to the lacrimal apparatus or ocu-

lar irritation by the contrast medium while performing the

CT-DCG; however, these were not noticed in the very limited

experience from this series. There would also be an additional

cost of acquiring 3D CT DCG scans, along with the added

cost of navigation-guided surgical procedure. Hence, its

utility of as now appears to be more cost-effective in complex

cases as presented in this series.

ConclusionThus, 3D CT-DCG guided navigation can provide a useful

radiological landmark while performing endoscopic DCRs

in cases with secondarily acquired and complex NLDOs.

Further large series, involving more varied etiopathologies,

would help in formulating appropriate guidelines for intra-

operative image guidance.

AcknowledgmentsWe acknowledge the help of Mr SBN Chary and Mr Gattu

Naresh with photography and Ms Sabera Banu in the litera-

ture search and retrieval of the same. Support provided by The

Operation Eyesight Universal Institute for Eye Cancer (SK),

Hyderabad, India, is acknowledged. The funders had no role

in the preparation, review or approval of the manuscript.

DisclosureMohammad Javed Ali receives royalties from Springer for his

text book “Principles and Practice of Lacrimal Surgery”. The

other authors report no conflicts of interest in this work.

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